Wrong distributor for 69 318?
Seen this. Put springs in to curve faster and cruising, and the engine would surge when trying to smooth cruise.
And you are running short curve w more initial? Jus makes it worse.
* Cruise AFR needs to be richened up.
If you had an AFB, it would be a rod change.
- opinions and assholes* - a lot out there.
- but, bet it will cure it.
Would like to know.
BUT, as far as points go, use a dwell meter.
My replacement dist. Ate the lubricated rubbing block down in less than 800 miles. Wore/ melted ? - nevertheless, messed me up for a while, couldn’t believe shi—. Stuff so cheap.
Yup. Unfortunately a lot poorly made junk out there.
Mystery distributor
So, I tried backing the initial timing all the way off to 0* TDC. It's a little bit better, but I'm still getting a lot of hesitation and stuttering that I didn't get with the vacuum advanced unplugged (this, mind you, is on 93 octane gas). Especially just off-idle
With that cam and the 4 bbl, I'm guessing 5 to 10* BTC would be a good starting point for idle.
Unplugged? I'm hoping you mean the line from the carburetor is plugged with a golf tee, or the port is capped.
If so, then PRH is giving a likely explanation to investigate.
If not, then what we're seeing is the engine likes that air leak under the throttle.
I've got it richened up quite a lot right now - 3 steps richer for cruise, and two stips richer on power (according to the edelbrock chart for me carb).
I also have an AFR gauge. AFR with the vacuum advance unplugged at cruise and idle is really rich - 11.5-12, down to 9-10 at WOT. With the advance plugged in, it
goes up to 14.2-14.8 at cruise. I'm assuming this is because it's pre-detonating from too much advance but I'm not sure.
Good to be suspicopus of the AFR readings in these cases. Timing doesn't change the actual AFR even if the WBO2 picked up a difference in oxygen,
Is it predetonating? Or is it just misfiring?
Detonation will occur under load and sound like gurgling or pinging. Under heavy load it can cause serious damage, but under light acceleration, damage is quite small if any. Small specs of aluminum will show on the porcelain when there has been detonation.
@PRH can probably be more specific. He's seen far more than I have.
Too early a spark can cause backfire through the carb. If spark is early and the intake valve is open, then backfire can occur.
Misfire will result in lots of unused O2 in the exhaust and yes the AFR meter will misinterpret the meaning of the higher O2 content.
On all of the carbs we're dealing with here, the jets and rods have little effect on idle and off-idle. They only really restrict fuel to the main venturies. Basically when the car is cruising at interstate speeds or when accelerating from 30 or 40 mph up. Off the line its the 'idle' or low speed circuits and acclerator pump.
